3D printed gears

[tenghensen]

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So I am trying to fab some spur gears for a pan motor on a camera positioner. It's going on a UAV and the entire payload will weigh less than 3lbs. I am trying to run the pan motion off a 12V motor rated at 470 rpm and 5mNm torque. The shaft for the pan is going to be supported on a simple ball bearing.

What I am trying to figure out is whether or not a 3D printer can make gears that will be approximately 3" and .5" that will be strong enough to handle the load and also give down to a 1 degree resolution considering the backlash. I have been looking into doing a 14.5 degree pressure angle to help with the resolution, but I am just not sure if the tooth size on the .5" gear will be large enough to allow the 3D printer to make them very accurately.

Any input would be helpful. Thanks

 

[MikeHalloran]

The general answer is 'no'.

The more specific answer is that it depends on which particular 3D printer, which process, and which raw material you are talking about.

No 3D printer of which I am aware is now capable of making decent small gears, but it is possible that the news has not reached me yet. It is also possible that a fully small gear capable 3D printer may be released next week; stranger things have happened.

... which means if you already have a 3D printer, you might as well go ahead and try, because the experience will be useful when the tool you want becomes possible.

There are some things you can try.
For instance, if backlash is a concern, you can try split teeth (each face a separate cantilever beam) and zero to negative lash, or the more conventional split gear with compression springs, or an elastic structure pressing the teeth toward zero lash.
You can also try combining features, e.g. a spur gear with integral crank arm or cam or whatever.

The real beauty of 3D printing is that there are no tooling costs, and a 'finished' part is only a day away, so you can ...

GO NUTS!


Mike Halloran
Pembroke Pines, FL, USA

 

[tbuelna]

Unless your budget for the project is extremely limited, why don't you just have a gear house machine them for you in the appropriate material and with the accuracy you require? It will not be that expensive.

Because 3D printed parts are built up from numerous layers of around .005" to .010", the "as-printed" surface quality and accuracy of a 3D printed gear tooth flank would probably not be satisfactory due to layer-to-layer mismatch.

For a one-off metal spur gear with low accuracy requirements, you could wire EDM the gear teeth. You would need to remove the recast layer from the EDM surfaces, but the process could also be used to improve the surface finish of the tooth flanks.

Hope that helps.
Terry

 

[Timelord]

If you want 1^O resolution I think your best bet is to use stock plastic gears from someplace like

https://sdp-si.com/eStore/Catalog/Group/207.

They will probably be cheaper than having them 3D printed unless you already have a printer. You should be able to find a gearset that will serve your needs.

Timelord

 

[tenghensen]

Thanks for the help everyone. @Timelord- The same day you made this post, I actually stumbled upon that same website and decided to just go with some of their products instead of fabbing my own. Very helpful link nonetheless.